Vascular disease, in particular cardiac infarction, is one of the most common fatal illnesses. It is caused by diseases of the coronary arteries (arteriosclerosis), in which the build-up of deposits (arteriosclerotic plaque) causes occlusions in the coronary arteries.
Nowadays, if coronary angiography reveals serious stenoses in the coronary arteries, causing angina pectoris which restricts the patient's capability and/or puts the patient at risk, a PTCA (percutaneous transluminal coronary angioplasty) is carried out in the majority of cases. This is done by expanding the narrowings in the coronary arteries using a so-called “balloon catheter”. In recent years, laser angioplasty (PTLA) has also become established for the removal of plaque from coronary arteries, particularly in cases of elongated stenoses (>2 cm), complete occlusion and in-stent restenoses.
Laser angioplasty means the removal of plaque using a thermal or non-thermal laser. The doctor does this by guiding a laser catheter until it reaches the stenosis in the coronary artery. The laser catheter consists of fine optical glass fibers. The laser energy causes photo-acoustic and photochemical processes that enable the plaque to be removed. In the thermal process, a laser balloon catheter destroys calcification by heating it to a temperature of 80 to 100 degrees for 15 seconds. This method is only used vary rarely today. In the non-thermal process, an ultraviolet-pulsed (308 nm) laser (excimer laser) is used. This pulsed laser results in the creation of vapor bubbles within a few hundred microseconds, causing explosive modification of the plaque. This process enables the plaque to be ablated in a controlled manner. The laser angioplasty can then be followed by a further PCTA and/or implantation of a stent.
U.S. Pat. No. 6,117,128 A discloses a device as mentioned above for laser angioplasty, in which an optical fiber for transmitting laser energy from a laser source to the point of treatment, runs in a first lumen of a catheter. A second lumen can accommodate a fiber for an optical coherence tomograph.
U.S. Pat. No. 6,660,001 B2 likewise describes a device as mentioned above, in which a plurality of glass fibers for radiating laser energy from a laser source, and a reflectance fiber, which is closely coupled to the optical reflectance system, are further disposed in the catheter.
A device for laser angioplasty is described, for example, in U.S. Pat. No. 5,093,877, “Optical Fiber Lasing Apparatus Lens” and in EP 0 355 200 A1 “Balloon dilatation catheter with laser cutting capability”. An example of a known product is the CVX-300® Excimer Laser System from Spectranetics, Colorado Springs, Colo., USA.